2018 GMC ACADIA Engine Problems

The warning light for a steering assist needs service came on the dash. The dealer had a code (po128) that pertained to a bad thermostat and coolant temp. sensor. The steering assist could have failed, along with possible engine damage. The dealer replaced the thermostat and the coolant temp sensor. Their were no police or insurance reports needed.

I have a 2018 GMC Acadia that is now displaying " shift to park " while the vehicle is in park. Upon extensive research I see GMC did issue a recall however, my particular VIN was not included. Its NOW displaying the error message which would lead me to believe it IS part of the recall. I called my local GMC dealership (Langhorne, PA.) and they said this was not covered since my VIN was not issues a recall.

A warning popped up on my dashboard stating "Power steering reduced. Drive with care." multiple times. Whenever the warning popped up, my air conditioning would stop working and my engine fan would run very loud. The warning would go off and back on over the course of a year. This started in the beginning of summer, 2024. On 4/3/25 I took it into an auto mechanic shop and after they looked at this warning, they confirmed that the thermostat has an issue where it gets stuck in the "open" position, therefore the thermostat isn't working properly and my car thinks it's over heating, when it's really not. If my car were to overheat while this thermostat wasn't working properly, my engine could overheat or worse. The thermostat part is being replaced today so after today, it won't be available for inspection upon request.

The contact owns a 2018 GMC Acadia. The contact stated that while driving at 60 MPH, the reduced engine power message was displayed. The RPM increased to high, and the engine revved. The accelerator pedal was depressed, but the vehicle failed to respond as needed. The contact stated that the failure was related to NHTSA Campaign Number: 18V358000 (Fuel System, Gasoline). The vehicle was taken to the local dealer, where it was determined that the high-pressure fuel pump needed to be replaced. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was approximately 98,000.

Mileage: 98,000

Sold 2018 GMC Acadia by LEE GMC in auburn. Acadias shift to park was defective, dealership replaced before sale did not disclose, shift to park and transmission malfunctions occurred. I returned Acadia to the dealership several times and they would never properly fix or address my concerns now my vehicle is unsafe to drive. I have documentation to support the claims in my letter, I can send as well if you’d like. Thank you Will send attachment

Truck lost power randomly while driving on freeway spend so much money on fixing it this has to do something with the way the built it

While car is in park, I get the "Shift To Park" warning after driving the vehicle.

A thermostat failure displays a "steering assist" warning while driving. The thermostat housing has been replaced twice in 3 years after this warning.

My steering assist is coming on an the thermostat play apart in this. The thermostat need to be change. 2018-GMC-Acadia are having problems with these parts.

Steering Assist is Reduced Drive with care. Everyone is have a problem with the 2018-GMC-Acadia thermostat is bad.

Seemingly at random a warning will pop up on the driver dashboard “Steering assist is reduced at this time”. This will lead to a engine coolant temp reading of 0 degrees, no a/c and reduced steering functionality. Through further investigation the OBD code P0128 tells us it’s a faulty Thermostat or Thermostat sensor. Even if you get these parts replaced, the issue still comes back. I’ve seen these exact complaints at least a thousand times across multiple years of this model/make 2016,2017,2018,2019. This is clearly a manufacturers fault and needs a recall before people get hurt.

The thermostat housing fails and is a known issue which causes the car to overheat and they said it will start of fire or shut down and loss of steering assist. The dealerships know about the issue and GMC does nothing leaving people with large repair bills or inoperable cars. the system won't let me upload my receipts here is the part #12678780 I was told by the dealership this is a known issue and they my emissions warranty only covers the thermostat but not the housing, but that they are 1 piece, playing games.....

bad torque converter lead to transmission replacement bad torque converter inspected by dealer car stopped starting difficulty shifting and catching up to speed while driving gmc california denied goodwill help

I have this 2018 Acadia where all of a sudden, at random, the radiator fan runs on high constantly, the AC stops blowing cold air, the thermostat gauge on the dash drops to the C, and the Power Assist is reduced and pops up as a message on the dash as well. Sounds like this may be a common problem among Acadia's. It resets at random and everything appears to be normal for a while. In addition, there are no check engine lights and no codes to check. I have had this happening for over a year and had a dealership service the car but never said mentioned it as a problem. So now that it's out of warranty my and has more frequent occurrences now I''m more aware but now it's out of warranty. It comes up on an Acadia Forum as a common issue. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I bought a used 2018 GMC Acadia in Oct. 2023. Initially the thermostat would go out and a check engine light would come on. This seems to be a common problem in GMC Acadia's and there are multiple blogs on this online (e.g. [XXX] ). INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The “steering assist reduced. Drive with care” A/C turns off and fan kicks on high. Transmission temp flatlines. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

We own a 2018 GMC Acadia Denali. Upon shifting the vehicle into park, we cannot turn off the engine. The vehicle gives us a "Shift to Park" message on the instrument panel. As a result, we are unable to shut off our engine and, to avoid the battery running out, are forced to attempt to move the shift lever in and out of "Park" to get the car to detect that the shift lever is in fact in ‘Park.’”

VEHICLE WILL NOT SHUT OFF AS IT SHOWS SHIFT TO PARK. REOCCURRING PROBLEM.

Mileage: 54,000

MY CAR KEEPS GIVING NOTICE OF IT NOT BEING IN PARK, WHEN ITS CLEARLY SHIFTED INTO PARK. IT WONT SHUT DOWN, LET YOU LOCK DOORS. JUST BEEPS UNTIL IT FINALLY REALIZES ITS IN PARK. EVEN AFTER CONTINUOUSLY RE SHIFTING INTO PARK. WORSE IN THE SUMMER MONTHS. IT NEEDS TO BE FIXED AS MANY OTHERS ARE HAVING THE SAME ISSUE! *TR

WHEN I SHIFT THE TO PARK AND TRY TO TURN OFF MY CAR THE SHIFT TO PARK LIGHTS UP AND I HAVE TO DOWN SHIFT AND THEN SHIFT TO PARK AGAIN TO GET MY CAR TO SHUT OFF ALSO THE AIR COMPRESSOR HAS ALREADY QUIT WORKING WITH LESS THAN 40K MILES ON IT. *TR

Mileage: 44,000

VEHICLE WILL NOT ACKNOWLEDGE THAT IT IS IN PARK. FORCES ELECTRICAL TO STAY ON, AND SOMETIMES WILL NOT ENGAGE PARK SO VEHICLE CAN MOVE AS IF I'M NEUTRAL. HAS THUS FAR HAPPENED WITH VEHICLE STOPPED, BUT YOU CAN SOMETIMES SHUT OFF ENGINE AND EXIT VEHICLE WHEN IT IS NOT IN PARK AND CAN ROLL AGAINST YOU, OR ON KIDS EXITING ETC. VEHICLE ROLLED IN GARAGE AND STRUCK, AND COULD HAVE CRUSHED CHILD AGAINST DOOR.

Mileage: 17,300

PUT CAR IN PARK WENT TO KILL IT AND IT WONT TURN OFF SAYS SHIFT TO PARK IT IS IN PARK HAD TO DO THIS LIKE 10 TIMES ..TWICE TODAY..MY CAR WONT TURN OFF FINALLY GOT IT OFF. I HAVE ONLY HAD THIS 2018 ACADIA LEAD THAN 1 MTH.. I HAVE READ WHERE THIS IS A BIG MAJOR ISSUE.. WHAT DO I DO

Mileage: 23,465

MULTIPLE OCCASIONS WHEN DRIVING VEHICLE, THEN ATTEMPTING TO SHIFT FROM DRIVE TO PARK AND ACTUALLY IN PARK AN ERROR COMES ON 'SHIFT TO PARK' COMES ON, I'VE TAKEN IT TO DEALERSHIP AND THEY BLAME ME ON SOME LIGHT BULBS I CHANGED, WELL I CHANGED THEM BACK AND STILL ERROR OCCURS. UNFORTUNATELY WHEN THAT HAPPENS I CAN'T LOCK MY VEHICLE FOR SOME TIME UNTIL MULTIPLE TIMES OF TURNING ON AND OFF THE VEHICLE. (2) WHILE DRIVING FORWARD, MY REAR CAMERA WOULD BE DISPLAYING LIVE EVERYTHING BEHIND ME, WHICH WAS VERY DISTRACTING, TOOK IT TO THE DEALERSHIP, I THINK THEY FIXED IT

Mileage: 10,000

MY 2018 GMC ACADIA SLT-1 HAS BEEN HAVING ACCELERATION ISSUES LIKE SHUDDERING AND OR FEELS LIKE A FULL LOSS OF POWER , WITH NO CHECK ENGINE LIGHT. I'VE TAKEN IT INTO THE DEALERSHIP TWICE FOR THIS PROBLEM . I'VE ONLY TAKEN IT IN THIS 2ND TIME BECAUSE IT GOT WORSE AND SCARED ME THAT IT WOULD DIE ON THE HIGHWAY. IT ALSO HAS HAD TO HAVE THE BATTERY CHARGED 3 TIMES IN A COUPLE OF WEEKS , YET THE DEALER SAYS THE BATTERY CHECKS GOOD. AT THE LEAST I BELIEVED SINCE ITS UNDER WARRANTY THEY WOULD CHANGE THE BATTERY IN THE CASE THE COMPUTER IS CAUSING ISSUES BASED ON BATTERY VOLTAGE. THE ALTERNATOR IS WORKING , BUT WITH ONLY 29K MILES NONE OF THIS BATTERY NOR ACCELERATION SHUDDER AND STUMBLE LIKE ITS GOING TO DIE SHOULD BE ACCEPTABLE.

Mileage: 29,100

WARNING MESSAGE SAYS "SHIFT TO PARK". MESSAGE DOES NOT GO OFF UNTIL YOU TURN CAR ON AND OFF SEVERAL TIMES; PUTTING THE CAR IN REVERSE, THEN DRIVE; THEN SHIFTING BETWEEN GEARS BACK AND FORTH. MAY TAKE 20 MINUTES TO GET THE MESSAGE LIGHT TO GO OFF. GMC HAS TRIED REPLACING GEAR SHIFT, PART OF GEAR TOP. AFTER 5 ATTEMPTS IN TRYING TO FIX THE ISSUE, MY CAR SITS AT THE DEALERSHIP FOR AN ADDITONAL 4 WEEKS WAITING FOR A HARNESS FIX (WHICH THERE IS NO PART FOR). THE CAR ALWAYS ROLLS BACKWARDS WHEN THE MESSAGE FINALLY GOES OFF. THIS IS A MAJOR SAFETY ISSUE. IS THE CAR REALLY IN PARK?

Mileage: 14,000

WHENEVER I SHIFT FROM DRIVER OR REVERSE INTO PARK MY CAR ISN'T REGISTERING THAT I SHIFTED TO PARK AND IF GIVING ME THE MESSAGE OF 'SHIFT TO PARK'. I HAD TO SHIFT FROM DRIVE TO PARK AT LEAST 4 TIMES TO BE ABLE TO GET MY CAR TO RECOGNIZE THAT MY CAR WAS IN PARK AND SO I COULD TURN OFF MY CAR.

Mileage: 37,000

"SHIFT TO PARK" ERROR 90% OF THE TIME WHEN I ATTEMPT TO SHUT THE VEHICLE OFF. IT IS IN PARK AND IT'S NOT RECOGNIZED AS BEING IN PARK. IT CAN TAKE ME ANYWHERE FROM 30 SECONDS TO 5 MINUTES TO JIGGLE IT THE RIGHT WAY TO GET IT TO REGISTER. PROBLEM IS UNTIL IT DOES REGISTER IN PARK I CAN'T SECURE THE VEHICLE. AND IT DINGS NONSTOP DRAINING THE BATTERY. I UNDERSTAND GM IS AWARE OF THE ISSUE AND DOESN'T HAVE A FIX. IT NEEDS A NEW TRANSMISSION IN MY OPINION. I'M STUCK IN A LEASE PAYING FOR A CAR THAT ISN'T SAFE FOR ME. IT JUST STARTED 6 DAYS AGO AND HAS ALREADY OCCURRED MORE THAN 2 DOZEN OCCASIONS.

Mileage: 18,754

1* PURCHASED MARCH 2018 (ACADIA DENALI) SINCE AUGUST 2018 IN MOTION WHEN I ACCELERATE IT SOUNDS LIKE A LOUD LAWNMOWER & CRACKLING SOUND IN REAR MUFFLER AREA. TOOK IT CHEVY PLACE IN GLENPOOL, OK. THEY COULDN'T FIND ANYTHING. 2* ON 2 OCCASSIONS, IN MOTION, THE CAR ACCELERATED WITH A LOUD NOISE & AS IF IT WERE GETTING POWER & NOT MOVING THEN JERKS & SPEEDS UP ABOUT 15MPH FASTER & I COULDN'T STOP IT. I KEPT SLAMMING ON MY BREAKS, BUT THE BREAK WOULD ONLY GO IN SO FAR. I WAS FRIGHTENED WITH MY 2 YOUNG BOYS IN CAR SCREAMING. IT'S LIKE RIDING A HORSE & IT TAKES OFF & YOU CAN'T CONTROL IT. 3* ON ABOUT 8 OR 9 OCCASSIONS STATIONARY I GET OUT OF MY CAR & IT MAKES A REALLY LOUD ANNOYING SOUND LIKE A MACHINE/ROBOT POWERING DOWN. MY KIDS ALWAYS SAY, IT'S GOING TO BLOW UP 4* THE MOST ANNOYING, FOR PAST MONTH...STATIONARY, EVERY SINGLE DAY & TIME I TURN MY IGNITION OFF. IT HAS LOUD BEEPING SOUND & CHECK REAR SEAT FLASHING ON SCREEN THEN SHIFT INTO PARK FLASHES. THIS OCCURS EVERY SINGLE TIME I TURN MY CAR OFF. SOMETIMES I HAVE TO JUST LET IT GO ON ALL DAY BECAUSE I CAN'T GET IT STOP. I TURN CAR ON & OFF SHIFT BACK & FORTH & IT STILL WILL NOT GO OFF. SOMETIMES IT DOES AFTER LONG PERIODS OF TIME. I DON'T HAVE TIME TO STRUGGLE WITH GETTING A CAR INTO PARK EVERY SINGLE TIME I TURN MY IGNITION OFF. I HAVE TO BEAT IT FORWARD HARD WITH MY HAND TO THE POINT MY WRIST IS BRUISED. NOW I HAVE TO USE MY FOOT TO KICK GEAR SHIFTER INTO PARK. I'M AFRAID T'S GOING TO ROLL OUT & OR DOWN AND HIT SOMETHING, SOMEONE OR EVEN ONE OF MY CHILDREN. WHICH WOULD NOT BE GOOD. I'VE SEEN SEVERAL OF SAME COMPLAINTS. THIS REALLY NEEDS TO BE INVESTIGATED & RECALLED ASAP. MY ELDERLY MOTHER HAD TO CALL MY BROTHER TO ANOTHER PART OF TOWN TO BEAT THE GEAR SHIFT INTO PARK. THIS CAR WAS BRAND NEW & I SHOULDN'T HAVE ANY OF THE ABOVE MENTIONED ISSUES. IT'S FRUSTRATING THINKING GMC WAS TOP OF THE LINE & IT'S NOT.

Mileage: 19,000

TL* THE CONTACT RENTED A 2018 GMC ACADIA. WHILE THE CONTACT'S FRIEND WAS DRIVING 40 MPH, THE ENGINE REVVED AND THE VEHICLE ACCELERATED ON ITS OWN. THE BRAKES FAILED TO STOP THE VEHICLE. AS A RESULT, THE VEHICLE DROVE THROUGH A PARTITION AND CRASHED INTO A BRICK WALL. THE AIR BAGS DEPLOYED. ALL FOUR OCCUPANTS IN THE VEHICLE WERE INJURED AND RECEIVED MEDICAL ATTENTION. THE CONTACT SUFFERED CHEST PAIN, ANOTHER OCCUPANT SUSTAINED A CUT ON THE HEAD, AND THE OTHER TWO OCCUPANTS SUFFERED FRACTURES. A POLICE REPORT WAS FILED. THE DEALER AND MANUFACTURER WERE NOT CONTACTED. THE CAUSE OF THE FAILURE WAS NOT DETERMINED. THE VEHICLE WAS DESTROYED AND TOWED TO A TOW LOT. THE FAILURE MILEAGE WAS UNKNOWN. .*BF .*BF 'PARTS OF THIS DOCUMENT HAVE BEEN REDACTED TO PROTECT PERSONALLY IDENTIFIABLE INFORMATION PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6).'*JB